Without sea-level acceleration, the 20th-century sea-level trend of 1.7 mm/y would produce a rise of only approximately 0.15 m from 2010 to 2100; therefore, sea-level acceleration is a critical component of projected sea-level rise. To determine this acceleration, we analyze monthly-averaged records for 57 U.S. tide gauges in the Permanent Service for Mean Sea Level (PSMSL) data base that have lengths of 60156 years. Least-squares quadratic analysis of each of the 57 records are performed to quantify accelerations, and 25 gauge records having data spanning from 1930 to 2010 are analyzed. In both cases we obtain small average sea-level decelerations. To compare these results with worldwide data, we extend the analysis of Douglas (1992) by an additional 25 years and analyze revised data of Church and White (2006) from 1930 to 2007 and also obtain small sea-level decelerations similar to those we obtain from U.S. gauge records.

Received: October 5, 2010; Accepted: November 26, 2010; Published Online: February 23, 2011

Sea-Level Acceleration Based on U.S. Tide Gauges and Extensions of Previous Global-Gauge Analyses, J. R. Houston and R. G. Dean

Discussion: (excerpt)

We analyzed the complete records of 57 U.S. tide gauges that had average record lengths of 82 years and records from1930 to 2010 for 25 gauges, and we obtained small decelerations of 20.0014 and20.0123 mm/y2, respectively. We obtained similar decelerations using worldwide-gauge records in the original data set of Church andWhite (2006) and a 2009 revision (for the periods of 19302001 and 19302007) and by extending Douglass (1992) analyses of worldwide gauges by 25 years.

The extension of the Douglas (1992) data from 1905 to 1985 for 25 years to 2010 included the period from 1993 to 2010 when satellite altimeters recorded a sea-level trend greater than that of the 20th century, yet the addition of the 25 years resulted in a slightly greater deceleration.

Conclusion:

Our analyses do not indicate acceleration in sea level in U.S. tide gauge records during the 20th century. Instead, for each time period we consider, the records show small decelerations that are consistent with a number of earlier studies of worldwide-gauge records. The decelerations that we obtain are opposite in sign and one to two orders of magnitude less than the +0.07 to +0.28 mm/y2 accelerations that are required to reach sea levels predicted for 2100 by Vermeer and Rahmsdorf (2009), Jevrejeva, Moore, and Grinsted (2010), and Grinsted, Moore, and Jevrejeva (2010). Bindoff et al. (2007) note an increase in worldwide temperature from 1906 to 2005 of 0.74uC.

It is essential that investigations continue to address why this worldwide-temperature increase has not produced acceleration of global sea level over the past 100 years, and indeed why global sea level has possibly decelerated for at least the last 80 years.

Some of the environmentalist's scare stories stay in fashion and some don't. I mean, whatever happened to "acid rain"?

Click to expand...

Environmental regulations. Whatever happened to knowing about a topic before posting? Limits on SO2 reduced the "acid rain" problem, just like banning CFCs led to the shrinking of the ozone hole. Funny how many deniers talk about "junk science". That's what they said about the two examples I gave. They just can't help being on the wrong side of science, history AND logic again, now that we're talking CO2 and GHGs.

Some of the environmentalist's scare stories stay in fashion and some don't. I mean, whatever happened to "acid rain"?

Click to expand...

Environmental regulations. Whatever happened to knowing about a topic before posting? Limits on SO2 reduced the "acid rain" problem, just like banning CFCs led to the shrinking of the ozone hole. Funny how many deniers talk about "junk science". That's what they said about the two examples I gave. They just can't help being on the wrong side of science, history AND logic again, now that we're talking CO2 and GHGs.

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